1. Field of the Invention
The present invention relates to a hood apparatus with a hood for opening and closing the engine room positioned in the front portion of a vehicle.
2. Description of the Related Art
A vehicle hood apparatus is configured to lift a hood a predetermined amount and retain it in the lifted position when a moving vehicle equipped with the apparatus collides with an object to be protected. The lifted hood can deform downward by an increased amount and absorb the collision energy through the deformation by an increased amount, thereby mitigating the impact of a secondary collision between the object to be protected and the top surface of the hood. A vehicle hood apparatus of such a kind is disclosed, for example, in Japanese Patent Laid-Open Publication No. HEI-9-315266.
When the vehicle collides with an object to be protected, this hood apparatus detects the collision with a collision detection sensor provided at the front bumper, raises a rod of a hood lifting and retaining mechanism through a control unit in response to the detection signal to bring a link mechanism upright by the rod, thereby lifting the rear end of the hood a predetermined amount and retaining it in the lifted position.
However, the object to be protected, after the collision with the vehicle, does not always encounter secondary collision with the top surface of the hood. In such a case, however, the lifted hood obstructs the driving vision of the driver. It is preferable that the obstruction of the driving vision by the lifted hood be speedily removed. This also applies to a case where the hood is erroneously lifted for some reason.
Further, the hood lifting and retaining mechanism of the above vehicle hood apparatus has a hook mounted to the rod or the vehicle body, being biased by a compression spring, which hook engages with the vehicle body to prevent the rod lifted a predetermined amount from descending, thereby retaining the hood in the lifted position.
As described above, the conventional hood apparatus retains the hood in the lifted position, and therefore has a complicated hooking mechanism consisting of the hook and the compression spring incorporated in the vehicle body. To incorporate such a hooking mechanism in the rod, the hood lifting and retaining mechanism becomes complicated and larger in its entirety, not being a smart solution. Further, to incorporate the hooking mechanism in the vehicle body, careful consideration is required for reliable hooking of the rod moving upward a predetermined amount at significantly high speed.
It is an object of the present invention to provide a vehicle hood apparatus of simple construction which can securely retain a hood in a lifted position.
It is another object of the present invention to provide a vehicle hood apparatus which can remove obstruction to the driving vision of a driver caused by a hood lifted upon collision between the vehicle and an object to be protected.
According to the present invention, there is provided a vehicle hood apparatus comprising: a hood for covering an engine room positioned in the front portion of a vehicle; a lifting actuator for lifting the rear end of the hood a predetermined amount when the vehicle collides with an object to be protected; and a hood retaining mechanism for retaining the hood in the lifted position; the hood retaining mechanism comprising: a bracket mounted to a body frame; a lower link swingably mounted to the bracket; an upper link swingably mounted to the rear end of the hood; a hinge for bendably and stretchably mounting the lower link and the upper link such that the hinge is offset forward relative to the vehicle; a stopper provided between the lower link and the bracket for preventing the lower link from falling rearward relative to the vehicle subsequent to the stretching of the lower link and the upper link; and a ratchet mechanism provided between the lower link and the bracket for allowing the lower link and the upper link to shift from a bending state to a stretching state while preventing the reverse shift.
Thus in the present invention, the lifting actuator is activated to lift the hood a predetermined amount, the lower link and the upper link stretch from the bending state. The stopper prevents the lower link from falling rearward relative to the vehicle. The ratchet mechanism blocks the lower link and the upper link from shifting from a stretching state to a bending state.
Thus the hood lifted is securely retained by the hood retaining mechanism.
The retaining mechanism eliminates the need for providing a lifting actuator as the hood lifting means with additional means for retaining the lifted hood, enabling the hood lifting means to be of a simplified structure.
The bracket is configured to buckle and deform when a downward load exceeding a predetermined amount acts thereon. For example, according to an embodiment of the present invention, a wall of the bracket is formed with a section C-shaped part. Specifically, when the bracket receives a downward load over a predetermined amount, the section C-shaped part buckles and deforms, thereby absorbing the force. Thus the impact on the object to be protected can be sufficiently mitigated.
The prevent invention is further provided with a pulling actuator for pulling the ratchet pawl of the ratchet mechanism in a disengaging direction. Upon the collision of the vehicle with the object to be protected or some other object, the hood is lifted. After the lapse of a predetermined period of time since the hood was lifted, it is determined that no secondary collision will occur between the object and the top surface of the hood. Then the ratchet mechanism is disengaged with the pulling actuator to return the hood to the original closing position. Alternately, after the hood is lifted upon the collision between the vehicle and the object to be protected, the pulling actuator is activated at will to disengage the ratchet mechanism, thereby returning the hood to the original position. Thus the obstruction of the driving vision of the driver caused by the lifted hood is speedily removed.